1. Field
Embodiments of the invention relate to a refrigerator, more particularly, to a refrigerator including a vacuum space formed between an outer case and an inner case to improve an insulation function thereof.
2. Background
A refrigerator is an electric home appliance can keep food stored in a storage compartment at a low temperature or a temperature below zero, using a refrigerant cycle.
A conventional configuration of such a refrigerator is provided with a case where a storage space is defined to store foods and a door rotatably or slidingly coupled to the case to open and close the storage space.
The case includes an inner case where the storage space is formed and an outer case configured to accommodate the inner case. An insulating material is arranged between the inner case and the outer case.
Such an insulating material suppresses the outdoor temperature from affecting an internal temperature of the storage space.
An example of the insulation material is urethane foams. Such urethane foams can be injection-foamed in the space formed between the inner and outer cases.
In this instance, to realize an insulation effect by using such the insulating material, a predetermined thickness of the insulating material has to be secured and that means that the insulating material becomes thick. Accordingly, a wall between the inner and outer cases becomes thick and the size of the refrigerator is increased as much as the thickness.
However, as a recent trend of a compact-sized refrigerator is one the rise, there is the need for the structure of the refrigerator that can make the volume of the internal storage space larger and the external size smaller.
Accordingly, the present invention proposes a refrigerator having a new structure which can perform insulation by forming a vacuum space, not by injecting the insulating material between the inner case and the outer case.
Meanwhile, vapors might be cooled and changed into frost in an evaporator composing a freezing cycle provided in the refrigerator. Such frost might be stuck to a surface of the evaporator. To solve such a problem of frost, a defrosting apparatus may be provided in the refrigerator to remove the frost by heating the frost to change it into water.
The water melted by the defrosting apparatus is exhausted to the outside of the refrigerator via a drainage pipe and such a drainage pipe is connected to the outside passing through the inner case, the outer case and the insulating material provided between the inner and outer cases.
Rather than such the drainage pipe, another pipe may be connected to the outside from the inside of the refrigerator.
In the conventional refrigerator having a foaming agent provided in the space between the inner case and the outer case, the pipe is simply connected to pass through the inner case, the insulating material and the outer case.
Accordingly, the pipe is molded of plastic and the plastic-molded pipe is disposed to pass the inner case and the outer case, and then the insulating material is foaming.
However, in the vacuum refrigerator according to the present invention, the pipe is connected to pass the vacuum space, with maintaining the airtight state of the vacuum space. If the plastic pipe is used, it is difficult to maintain the airtight state at the connection area between the pipe and the vacuum space and the connection area cannot endure the vacuum pressure of the vacuum space disadvantageously.
Moreover, if the pipe is formed of a metal pipe capable of being welded to the inner case and the outer case formed of a steel sheet, heat transfer might be generated via the pipe and an insulation performance of the refrigerator might be deteriorated accordingly.